Atomic bombings of Hiroshima and Nagasaki

Atomic bombings of Hiroshima and NagasakiFrom Wikipedia, the free encyclopediaThe mushroom cloud over Hiroshima after the dropping of Little Boy The Fat Man mushroom cloud resulting from the nuclear explosion over Nagasakirises 18 km (11 mi,60,000 ft) into the air fromthe hypocenter .The atomic bombings of Hiroshima and Nagasaki were nuclear attacks near the end of World War II against the Empire of Japan by the United States at the executive order of U.S. President Harry S. Truman on August 6 and August 9, 1945, respectively. After six months of intense fire-bombing of 67 other Japanese cities , followed by an ultimatum which was ignored by the Shōwa regime , the nuclear weapon "Little Boy " was dropped on the city of Hiroshima on Monday,[1] August 6, 1945, [2] followed on August 9 by the detonation of the "Fat Man " nuclear bomb over Nagasaki . These are theonly attacks with nuclear weapons in the history of warfare.[3]The bombs killed as many as 140,000 people in Hiroshima and 80,000 in Nagasaki by the end of 1945,[4] with roughly half of those deaths occurring on the days of the bombings. Amongst these, 15–20% died from injuries or the combined effects of flash burns, trauma, and radiation burns, compounded by illness, malnutrition and radiation sickness .[5] Since then, more have died from leukemia (231 observed) and solid cancers (334 observed) attributed to exposure to radiation released by the bombs.[6] In both cities, most of the dead were civilians.[7][8][9]Six days after the detonation over Nagasaki, on August 15, Japan announced its surrender to the Allied Powers, signing the Instrument of Surrender on September 2, officially ending the Pacific War and therefore World War II. (Germany had signed its unavoidable[2]Instrument of Surrender on May 7, ending the war in Europe.) The bombings led, in part, to post-war Japan adopting Three Non-Nuclear Principles, forbidding that nation from nuclear armament.[10]The Manhattan ProjectThe United States, in collaboration with the United Kingdom and Canada, with their respective secret projects Tube Alloys and Chalk River Laboratories,[11][12] designed and built the first atomic bombs under what was called the Manhattan Project. The scientific research was directed by American physicist J. Robert Oppenheimer. The Hiroshima bomb, a gun-type bomb called "Little Boy", was made with uranium-235, a rare isotope of uranium. The atomic bomb was first tested at Trinity Site, on July 16, 1945, near Alamogordo, New Mexico. The test weapon, "the gadget," and the Nagasaki bomb, "Fat Man," were both implosion-type devices made primarily of plutonium-239, a synthetic element.[13]Choice of targetsOn May 10–11, 1945 The Target Committee at Los Alamos, led by J. Robert Oppenheimer, recommended Kyoto, Hiroshima, Yokohama, and the arsenal at Kokura as possible targets. The target selection was subject to the following criteria:∙The target was larger than three miles in diameter and was an important target in a large urban area.∙The blast would create effective damage.∙The target was unlikely to be attacked by August 1945. "Any small and strictly military objective should be located in a much larger area subject to blast damage in order to avoid undue risks of the weapon being lost due to bad placing of the bomb."[14]These cities were largely untouched during the nightly bombing raids and the Army Air Force agreed to leave them off the target list so accurate assessment of the weapon could be made. Hiroshima was described as "an important army depot and port of embarkation in the middle of an urban industrial area. It is a good radar target and it is such a size that a large part of the city could be extensively damaged. There are adjacent hills which are likely to produce a focussing effect which would considerably increase the blast damage. Due to rivers it is not a goodincendiary target."[14] The goal of the weapon was to convince Japan to surrender unconditionally in accordance with the terms of the Potsdam Declaration. The Target Committee stated that "It was agreed that psychological factors in the target selection were of great importance. Two aspects of this are (1) obtaining the greatest psychological effect against Japan and (2) making the initial use sufficiently spectacular for the importance of the weapon to be internationally recognized when publicity on it is released. In this respect Kyoto has the advantage of the people being more highly intelligent and hence better able to appreciate the significance of the weapon. Hiroshima has the advantage of being such a size and with possible focussing from nearby mountains that a large fraction of the city may be destroyed. The Emperor's palace in Tokyo has a greater fame than any other target but is of least strategic value."[14]During World War II, Edwin O. Reischauer was the Japan expert for the US Army Intelligence Service, in which role he is incorrectly said to have prevented the bombing of Kyoto.[15] In his autobiography, Reischauer specifically refuted the validity of this broadly-accepted claim:"...the only person deserving credit for saving Kyoto from destruction is Henry L.Stimson, the Secretary of War at the time, who had known and admired Kyoto ever since his honeymoon there several decades earlier."[16]The Potsdam ultimatumOn July 26, Truman and other allied leaders issued the Potsdam Declaration outlining terms of surrender for Japan. It was presented as an ultimatum and stated that without a surrender, the Allies would attack Japan, resulting in "the inevitable and complete destruction of the Japanese armed forces and just as inevitably the utter devastation of the Japanese homeland". The atomic bomb was not mentioned in the communique. On July 28, Japanese papers reported that the declaration had been rejected by the Japanese government. That afternoon, Prime Minister Kantaro Suzuki declared at a press conference that the Potsdam Declaration was no more than a rehash (yakinaoshi) of the Cairo Declaration and that the government intended to ignore it (mokusatsu lit. "kill by silence").[17] The statement was taken by both Japanese and foreign papers as a clear rejection of the declaration. Emperor Hirohito, who was waiting for a Soviet reply to noncommittal Japanese peace feelers, made no move to change the government position.[18]On July 31, he made clear to his advisor Kōichi Kido that the Imperial Regalia of Japan had to be defended at all costs.[19]In early July, on his way to Potsdam, Truman had re-examined the decision to use the bomb. In the end, Truman made the decision to drop the atomic bombs on Japan. His stated intention in ordering the bombings was to bring about a quick resolution of the war by inflicting destruction and instilling fear of further destruction in sufficient strength to cause Japan to surrender.[20]HiroshimaHiroshima during World War IIThe Enola Gay and its crew, who dropped the "Little Boy" atomic bomb on Hiroshima.At the time of its bombing, Hiroshima was a city of some industrial and military significance. A number of military camps were located nearby, including the headquarters of the Fifth Division and Field Marshal Shunroku Hata's 2nd General Army Headquarters, which commanded the defense of all of southern Japan. Hiroshima was a minor supply and logistics base for the Japanese military. The city was a communications center, a storage point, and an assembly area for troops. It was one of several Japanese cities left deliberately untouched by American bombing, allowing a pristine environment to measure the damage caused by the atomic bomb.[citation needed]The center of the city contained several reinforced concrete buildings and lighter structures. Outside the center, the area was congested by a dense collection of small wooden workshops set among Japanese houses. A few larger industrial plants lay near the outskirts of the city. The houses were constructed of wood with tile roofs, and many of the industrial buildings were also built around wood frames. The city as a whole was highly susceptible to fire damage.The population of Hiroshima had reached a peak of over 381,000 earlier in the war, but prior to the atomic bombing the population had steadily decreased because of a systematic evacuation ordered by the Japanese government. At the time of the attack the population was approximately 340,000-350,000.[4] Because official documents were burned, the exact population is uncertain.The bombingFor the composition of the USAAF mission see 509th Composite Group.Seizo Yamada's ground level photo taken from approximately 7 km northeast of Hiroshima.Hiroshima was the primary target of the first nuclear bombing mission on August 6, with Kokura and Nagasaki being alternative targets. August 6 was chosen because clouds had previously obscured the target. The 393d Bombardment Squadron B-29Enola Gay, piloted and commanded by 509th Composite Group commander Colonel Paul Tibbets, was launched from North Field airbase on Tinian in the West Pacific, about six hours flight time from Japan. The Enola Gay (named after Colonel Tibbets' mother) was accompanied by two other B29s. The Great Artiste, commanded by Major Charles W. Sweeney, carried instrumentation; and a then-nameless aircraft later called Necessary Evil (the photography aircraft) was commanded by Captain George Marquardt.[21]After leaving Tinian the aircraft made their way separately to Iwo Jima where they rendezvoused at 2,440 meters (8,000 ft) and set course for Japan. The aircraft arrived over the target in clear visibility at 9,855 meters (32,330 ft). During the journey, Navy Captain William Parsons had armed the bomb, which had been left unarmed to minimize therisks during takeoff. His assistant, 2nd Lt. Morris Jeppson, removed the safety devices 30 minutes before reaching the target area.[22]About an hour before the bombing, Japanese early warning radar detected the approach of some American aircraft headed for the southern part of Japan. An alert was given and radio broadcasting stopped in many cities, among them Hiroshima. At nearly 08:00, the radar operator in Hiroshima determined that the number of planes coming in was very small—probably not more than three—and the air raid alert was lifted. To conserve fuel and aircraft, the Japanese had decided not to intercept small formations. The normal radio broadcast warning was given to the people that it might be advisable to go to air-raid shelters if B-29s were actually sighted, but no raid was expected beyond some sort of reconnaissance.The energy released was powerful enough to burn through clothing. The dark portions of the garments this victim wore at the time of the blast were emblazoned on to the flesh as scars.[23]The release at 08:15 (Hiroshima time) went as planned, and the gravity bomb known as "Little Boy", a gun-type fission weapon with 60 kilograms (130 lb) of uranium-235, took 57 seconds to fall from the aircraft to the predetermined detonation height about 600 meters (2,000 ft) above the city. Due to crosswind, it missed the aiming point, the Aioi Bridge, by almost 800 feet (240 m) and detonated directly over Shima Surgical Clinic.[24] It created a blast equivalent to about 13 kilotons of TNT (54 TJ). (The U-235 weapon was considered very inefficient, with only 1.38% of its material fissioning.)[25]The radius of total destruction was about one mile (1.6 km), with resulting fires across 4.4 square miles (11 km2).[26]Americans estimated that 4.7 square miles (12 km2) of the city were destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged.[5]70,000–80,000 people, or some 30%[27]of the population of Hiroshima were killed immediately, and another 70,000 injured.[28]Over 90% of the doctors and 93% of the nurses in Hiroshima were killed or injured—most had been in the downtown area which received the greatest damage.[29]Although the United States had previously dropped leaflets warning civilians of air raids on twelve other Japanese cities,[30] the residents of Hiroshima were given no notice of the atomic bomb.[31][32][33]Japanese realization of the bombingHiroshima before the bombing. Hiroshima after the bombing. The Tokyo control operator of the Japanese Broadcasting Corporation noticed that the Hiroshima station had gone off the air. He tried to re-establish his program by using another telephone line, but it too had failed.[34] About twenty minutes later the Tokyo railroad telegraph center realized that the main line telegraph had stopped working just north of Hiroshima. From some small railway stops within 16 kilometers (10 mi) of the city came unofficial and confused reports of a terrible explosion in Hiroshima. All these reports were transmitted to the headquarters of the Imperial Japanese Army General Staff .Military bases repeatedly tried to call the Army Control Station in Hiroshima. The complete silence from that city puzzled the men atheadquarters; they knew that no large enemy raid had occurred and that no sizeable store of explosives was in Hiroshima at that time. A young officer of the Japanese General Staff was instructed to fly immediately to Hiroshima, to land, survey the damage, and return to Tokyo with reliable information for the staff. It was generally felt at headquarters that nothing serious had taken place and that the explosion was just a rumor. The staff officer went to the airport and took off for the southwest. After flying for about three hours, while still nearly one hundred miles (160 km) from Hiroshima, he and his pilot saw a great cloud of smoke from the bomb. In the bright afternoon, the remains of Hiroshima were burning. Theirplane soon reached the city, around which they circled in disbelief. A great scar on the land still burning and covered by a heavy cloud of smoke was all that was left. They landed south of the city, and the staff officer, after reporting to Tokyo, immediately began to organize relief measures.By August 8, 1945, newspapers in the US were reporting that broadcasts from Radio Tokyo had described the destruction observed in Hiroshima. "Practically all living things, human and animal, were literally seared to death," Japanese radio announcers said in a broadcast captured by Allied sources.[35]Post-attack casualtiesAccording to most estimates, the immediate effects of the blast killed approximately 70,000 people in Hiroshima. Estimates of total deaths by the end of 1945 from burns, radiation and related disease, the effects of which were aggravated by lack of medical resources, range from 90,000 to 140,000.[4][36] Some estimates state up to 200,000 had died by 1950, due to cancer and other long-term effects.[1][7][37]Another study states that from 1950 to 1990, roughly 9% of the cancer and leukemia deaths among bomb survivors was due to radiation from the bombs, the statistical excess being estimated to 89 leukemia and 339 solid cancers.[38] At least eleven known prisoners of war died from the bombing.[39]Survival of some structuresSmall-scale recreation of the Nakajima area around ground zero.Some of the reinforced concrete buildings in Hiroshima had been very strongly constructed because of the earthquake danger in Japan, and their framework did not collapse even though they were fairly close to the blast center. Eizo Nomura (野村英三Nomura Eizō?) was the closest known survivor, who was in the basement of a modern "Rest House" only 100 m (330 ft) from ground-zero at the time of the attack.[40]Akiko Takakura (高蔵信子Takakura Akiko?) was among the closest survivors to the hypocenter of the blast. She had been in the solidly built Bank of Hiroshima only 300 meters (980 ft) from ground-zero at the time of the attack.[41] Since the bomb detonated in the air, the blast was directed more downward than sideways, which was largely responsible for the survival of the Prefectural Industrial Promotional Hall, now commonly known as the Genbaku, or A-bomb Dome. This building was designed and built by the Czech architect Jan Letzel, and was only 150 m (490 ft) from ground zero (the hypocenter). The ruin was named Hiroshima Peace Memorial and was made a UNESCO World Heritage site in 1996 over the objections of the U.S. and China.[42]Events of August 7-9After the Hiroshima bombing, President Truman announced, if they do not now accept our terms, they may expect a rain of ruin from the air the likes of which has never been seen on this earth.The Japanese government still did not react to the Potsdam Declaration. Emperor Hirohito, the government, and the war council were considering four conditions for surrender: the preservation of the kokutai(Imperial institution and national polity), assumption by the Imperial Headquarters of responsibility for disarmament and demobilization, no occupation of the Japanese Home Islands, Korea, or Formosa, and delegation of the punishment of war criminals to the Japanese government.[43]The Soviet Foreign Minister Molotov had informed Tokyo of the Soviet Union's unilateral abrogation of the Soviet-Japanese Neutrality Pact on April 5. At two minutes past midnight on August 9, Tokyo time, Soviet infantry, armor, and air forces had launched the Manchurian Strategic Offensive Operation. Four hours later, word reached Tokyo that the Soviet Union had declared war on Japan. The senior leadership of the Japanese Army began preparations to impose martial law on the nation, with the support of Minister of War Korechika Anami, in order to stop anyone attempting to make peace.Responsibility for the timing of the second bombing was delegated to Colonel Tibbets as commander of the 509th Composite Group on Tinian. Scheduled for August 11 against Kokura, the raid was moved earlier by two days to avoid a five day period of bad weather forecast to begin on August 10.[44] Three bomb pre-assemblies had been transported to Tinian, labeled F-31, F-32, and F-33 on their exteriors. On August 8, a dress rehearsal was conducted off Tinian by Maj. Charles Sweeney using Bockscar as the drop airplane. Assembly F-33 was expended testing the components and F-31 was designated for the August 9 mission.[45]NagasakiNagasaki during World War IIThe Bockscar and its crew, who dropped the "Fat Man" atomic bomb on Nagasaki.The city of Nagasaki had been one of the largest sea ports in southern Japan and was of great wartime importance because of its wide-ranging industrial activity, including the production of ordnance, ships, military equipment, and other war materials.In contrast to many modern aspects of Hiroshima, almost all of the buildings were of old-fashioned Japanese construction, consisting of wood or wood-frame buildings with wood walls (with or without plaster) and tile roofs. Many of the smaller industries and business establishments were also situated in buildings of wood or other materials not designed to withstand explosions. Nagasaki had been permitted to grow for many years without conforming to any definite city zoning plan; residences were erected adjacent to factory buildings and to each other almost as closely as possible throughout the entire industrial valley.Nagasaki had never been subjected to large-scale bombing prior to the explosion of a nuclear weapon there. On August 1, 1945, however, a number of conventional high-explosive bombs were dropped on the city. A few hit in the shipyards and dock areas in the southwest portion of the city, several hit the Mitsubishi Steel and Arms Works, and six bombs landed at the Nagasaki Medical School and Hospital, with three direct hits on buildings there. While the damage from these bombs was relatively small, it created considerable concern in Nagasaki and many people—principally school children—were evacuated to rural areas for safety, thus reducing the population in the city at the time of the nuclear attack.To the north of Nagasaki there was a camp holding British Commonwealth prisoners of war, some of whom were working in the coal mines and only found out about the bombing when they came to the surface. At least eight known POWs died from the bombing and as many as thirteen POWs may have died:∙One British Commonwealth citizen[46][47][48][49][50]∙Seven Dutch POWs (two names known)[51] died in the bombing.∙At least two POWs reportedly died postwar from cancer thought to have been caused by the atomic bomb.[52][53]The bombingFor the composition of the USAAF mission see 509th Composite Group.A post-war "Fat Man" model.On the morning of August 9, 1945, the U.S. B-29 Superfortress Bockscar, flown by the crew of 393rd Squadron commander Major Charles W. Sweeney, carried the nuclear bomb code-named "Fat Man", with Kokura as the primary target and Nagasaki the secondary target. The mission plan for the second attack was nearly identical to that of the Hiroshima mission, with two B-29s flying an hour ahead as weather scouts and two additional B-29s in Sweeney's flight for instrumentation and photographic support of the mission. Sweeney took off with his weapon already armed but with the electrical safety plugs still engaged.[54]Observers aboard the weather planes reported both targets clear. When Sweeney's aircraft arrived at the assembly point for his flight off the coast of Japan, the third plane, Big Stink, flown by the group's Operations Officer, Lt. Col. James I. Hopkins, Jr. failed to make the rendezvous. Bockscar and the instrumentation plane circled for forty minutes without locating Hopkins. Already 30 minutes behind schedule, Sweeney decided to fly on without Hopkins.[54]Nagasaki before and after bombing.By the time they reached Kokura a half hour later, a 70% cloud cover had obscured the city, prohibiting the visual attack required by orders. After three runs over the city, and with fuel running low because a transfer pump on a reserve tank had failed before take-off, they headed for their secondary target, Nagasaki.[54]Fuel consumption calculations made en route indicated that Bockscar had insufficient fuel to reach Iwo Jima and would be forced to divert to Okinawa. After initially deciding that if Nagasaki were obscured on their arrival the crew would carry the bomb to Okinawa and dispose of it in the ocean if necessary, the weaponeer Navy Commander Frederick Ashworth decided that a radar approach would be used if the target was obscured.[55]At about 07:50 Japanese time, an air raid alert was sounded in Nagasaki, but the "all clear" signal was given at 08:30. When only two B-29 Superfortresses were sighted at 10:53, the Japanese apparently assumed that the planes were only on reconnaissance and no further alarm was given.A few minutes later at 11:00, The Great Artiste, the support B-29 flown by Captain Frederick C. Bock, dropped instruments attached to three parachutes. These instruments also contained an unsigned letter to Professor Ryokichi Sagane, a nuclear physicist at the University of Tokyo who studied with three of the scientists responsible for the atomic bomb at the University of California, Berkeley, urging him to tell the public about the danger involved with these weapons of mass destruction. The messages were found by military authorities but not turned over to Sagane until a month later.[56] In 1949 one of the authors of the letter, Luis Alvarez, met with Sagane and signed the document.[57]A Japanese report on the bombing characterized Nagasaki as "like a graveyard with not a tombstone standing".At 11:01, a last minute break in the clouds over Nagasaki allowed Bockscar's bombardier, Captain Kermit Beahan, to visually sight the target as ordered. The "Fat Man" weapon, containing a core of ~6.4 kg (14.1 lbs.) of plutonium-239, was dropped over the city's industrial valley. Forty-three seconds later it exploded 469 meters (1,540 ft) abovethe ground exactly halfway between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works (Torpedo Works) in the north. This was nearly 3 kilometers (2 mi) northwest of the planned hypocenter; the blast was confined to the Urakami Valley and a major portion of the city was protected by the intervening hills.[58] The resulting explosion had a blast yield equivalent to 21 kilotons of TNT (88 TJ).[citation needed]The explosion generated heat estimated at 3,900 degrees Celsius (4,200 K, 7,000 °F) and winds that were estimated at 1005 km/h (624 mph).Casualty estimates for immediate deaths range from 40,000 to 75,000.[59][60][61] Total deaths by the end of 1945 may have reached 80,000.[4] The radius of total destruction was about a mile (1–2 km), followed by fires across the northern portion of the city to two miles (3 km) south of the bomb.[62][63]An unknown number of survivors from the Hiroshima bombing had made their way to Nagasaki, where they were bombed again.[64][65]The Mitsubishi-Urakami Ordnance Works, the factory that manufactured the type 91 torpedoes released in Pearl Harbor, was subsequently destroyed in the blast.[66]Plans for more atomic attacks on JapanThe United States expected to have another atomic bomb ready for use in the third week of August, with three more in September and a further three in October.[67]On August 10, Major General Leslie Groves, military director of the Manhattan Project, sent a memorandum to General of the Army George Marshall, Chief of Staff of the United States Army, in which he wrote that "the next bomb . . should be ready for delivery on the first suitable weather after 17 or August 18." On the same day, Marshall endorsed the memo with the comment, "It is not to be released over Japan without express authority from the President."[67]There was already discussion in the War Department about conserving the bombs in production until Operation Downfall, the projected invasion of Japan, had begun. "The problem now [August 13] is whether or not, assuming the Japanese do not capitulate, to continue dropping them every time one is made and shipped out there or whether to hold them . . . and then pour them all on in a reasonably short time. Not all in one day, but over a short period. And that also takes into consideration the target that we are after. In other words, should we not concentrate on targets that will be of the greatest assistance to an invasion rather than industry, morale, psychology, and the like? Nearer the tactical use rather than other use."[67]The surrender of Japan and subsequent occupation Main articles: Surrender of Japan and Occupation of JapanUntil August 9, the war council had still insisted on its four conditions for surrender. On that day Hirohito ordered Kido to "quickly control the situation ... because the Soviet Union has declared war against us." He then held an Imperial conference during which he authorized minister Tōgōto notify the Allies that Japan would accept their terms on one condition, that the declaration "does not compromise any demand which prejudices the prerogatives of His Majesty as a Sovereign ruler."[68]On August 12, the Emperor informed the imperial family of his decision to surrender. One of his uncles, Prince Asaka, then asked whether the war would be continued if the kokutai could not be preserved. Hirohito simply replied "of course."[69] As the Allied terms seemed to leave intact the principle of the preservation of the Throne, Hirohito recorded on August 14 his capitulation announcement which was broadcast to the Japanese nation the next day despite a short rebellion by militarists opposed to the surrender.In his declaration, Hirohito referred to the atomic bombings: “Moreover, the enemy now possesses a new and terrible weapon with the power to destroy many innocent lives and do incalculable damage. Should we continue tofight, not only would it result in an ultimate collapse and obliteration of the Japanesenation, but also it would lead to the total extinction of human civilization.Such being the case, how are We to save the millions of Oursubjects, or to atone Ourselves before the hallowed spirits ofOur Imperial Ancestors? This is the reason why We have orderedthe acceptance of the provisions of the Joint Declaration ofthe Powers. ”In his "Rescript to the soldiers and sailors" delivered on August 17, he stressed the impact of the Soviet invasion and his decision to surrender, omitting any mention of the bombs.During the year after the bombing, approximately 40,000 U.S. troops occupied Hiroshima, while Nagasaki was occupied by 27,000 troops.。